Color-and-tone-correcting separation film



15, 1970 MAURER ETAL 354K639 I COLOR AND IYONE-C0RRECTING SEPARATION FILM Filed Sept. 1. 1966 GREEN -SENSITIZED SILVER HAL IOE EMULSION CLEAR //v TERLAYER rPm-sL'A/s/r/zw S/Ll/ER HAL/DE EMULSION \CLEAI? SUPPORT ANT/HALAT/O/V LA YER BLUE ABSORB/IVG FILTER 2/ PAIVOHROMATICALLY SENS/T/ZED SILVER HAL/0E EMULSION GREEN ABSORB/IVG FILTER OR THOOHROMA T/OALLY SEA/SI T IZEO SILVER HAL/DE EMULSION Z4 v CLEAR SUPPORT AN T/HALAT/O/V LAYER 26 l6 2 BLUE ABSORB/A/G. FILTER ORTHOCHROMAT/CALLY .SEA/S/T/ZEO SILVER HAL/OE EMULSION BLUE ABSORBING FILTER BLUE -SEIVLS ITIVE SILVER HAL/DE EMULSION CLEAR SUPPORT ANT/HALAT/O/V LAYER ULTRAVIOLET ABSORBIIVG FILTER BLUE B GRE/V.SE/V$/T/VE 57!. m? HAL/DE EMULSION. BLUE ABBUPB/NB F/L 775B BLUE B RED-SENSITIVE SILVER HAL/DE EMULSION CLEAR suPPoPr A/VT/HALAT/O/V LAYBP 5/ PA/VCHROMATICALLY SE/VS/T/ZED S/L VEI? HAL/DE EMUL s/0/v SHARP CUTTING AT ABOUT 600 07/}! 52 K/F/LTER WITH SHARP cur OFF mam/w MAL/R5,?

- AT 560 07/, I ALLA/V G. MILL/KAN mvrsyToRs PA/VCH/POMAWCAL LY SENS/T1250 .SlLl/ER HAL/0E EMULB/UA/ j L CLEAR SUPPORT F u L A/VT/HALAT/O/V LAYER LQTTOfi/VEY 3 AGE/VT US. Cl. 96-69 16 Claims ABSTRACT OF THE DISCLOSURE A light-sensitive black-and-white photographic separation negative film comprising:

( 1) a transparent support having coated thereon:

(2) a first light-sensitive layer that is a color-andtone correcting silver separation-negative-imageforming layer containing a hydrophilic colloid silver halide emulsion that is capable of recording a light image of at least one primary color; and

(3) a removable superposed silver-image-forming layer that is capable of recording a light image of at least one primary color that is dilferent from that recorded by said first layer, said removable layer containing silver halide with at least one mole percent more iodine than said silver halide in said first layer; is advantageously used to prepare a unitary colorand tone-correcting silver separation negative image of a multicolor original image by the process steps of:

(a) exposing to an original;

(b) development of a unitary color-and-tone-correcting-separation-negative image in said first layer and a silver negative image in said removable layer; and

(c) removal of said removable layer, leaving said unitary color and tone-correcting-separation negative as the sole image in the processed film.

This invention relates to the photomechanical preparation of plates for color printing. In a more specific aspect the invention concerns improved processes and light-sensitive materials for making color-separation images which are color-and-tone corrected for use in making color printing plates.

The photomechanical reproduction of a colored original typically involves the'preparation of three color separations by photographing the original on three separate panchromatic films or plates, making one exposure through a red, a second through a green, and the third through a blue filter. The resulting latent images are processed to black-and-White color separation images which are then used for the preparation of three separate printing plates. These printing plates are inked, each with a different subtractively colored ink and printed, in register on paper. The plate made from the red-filter separation is printed with cyan ink, the plate from the green separation, with magenta ink, and the plate from the blue separation with yellow ink. In so-called four-color printing, a black-ink printing is added to the three colors to improve the sharpness and the density in the neutral areas of the reproduction. The black printer is made from a specially prepared black separation.

In all known methods of photomechanical color reproduction, there is a loss in color fidelity resulting from deficiencies inherent in the printing inks because each of the three inks absorbs appreciable amounts of wavelengths of light which it should transmit or reflect. Thus the magenta ink which should absorb only green light, also absorbs some blue light and some red light, thus nited States Patent behaving as though it were degraded with a little yellow and a little cyan ink. The cyan ink similarly behaves as though it were contaminated with a little yellow and a little magenta ink, for it absorbs some of the blue and also some of the green light which it should transmit. Yellow process inks exhibit less unwanted absorption than do the magenta and cyan inks. At present, the unwanted absorptions of printing inks cannot be eliminated; they are inherent characteristics of even the best colorants available to ink manufacturers.

It is customary in making printing plates for high quality color printing to compensate for these deficiencies of the printing inks by providing each of the separation films with a photographically prepared mask. Photographic masking techniques for the color and tone correction of separation images are complicated, and usually they require separate masking films and an intricate sequence of steps including exposing, processing and reregistering the mask image.

The photographic masking of separation films has been simplified by the use of masking materials which make it possible to prepare a number of color-correcting masks in a single photographic element, as described, for example, in US. Pat. 2,382,690 and 2,367,351, British Pat. 385,258, and German Pats. 1,086,552 and 1,058,839. While such materials eliminate the need for several separate masks, they still require not only the preparation of a separate film, but also the use of special processing solutions and extra processing operations; and most important, they require a precise registration of the separately prepared mask with the corresponding separation image. A high degree of skill is required to prepare and use such composite masks.

U.S. Pats. 2,179,786 and 2,218,229 disclose color-separation materials comprising, in addition to the usual emulsion layers in which the separation negative is formed, a second photosensitive layer which, after reversal development, remains attached to the film in the form of an integral positive mask. According to these techniques, the separation images are color-corrected by differential absorption of the exposing light by the mask element, and the images exposed onto the printing plate material com prise the separation negative image which is superposed with a positive mask.

While such integral masks offer certain advantages, they still require additional processing steps for preparing both the separation image and the mask image, the two images are physically separated in different layers so that special precautions are required to obviate unwanted optical edge efiects. There is considerable advantage in a system for the color-and-tone-correction of color separation images which obviates separate processing of a mask and which produces an integral silver color-separation image incorporating the color-and-tone corrections as point-to-point modifications in density rather than by way of a second and distinct silver image in an overlayer.

We have invented photographic materials and processes which cooperate to provide such integrally color-and-tonecorrected-seperation images in the form of a unitary silver image in a single layer which compensates for the unwanted absorptions of conventional printing inks.

It is an object of our invention to provide novel colorand-tone-correcting color-separation elements for the photomechanical preparation of improved color reproductions.

A second object is to provide a novel process for the preparation of color-and-tone-corrected color-separation images,

A further object is to prepare novel color-and-tonecorrected separation films which can be processed by a single black-and-white development step.

Another object is to provide novel photographic elements which provide integral silver color-separation images that compensate for the unwanted absorptions of printing inks. Another object is to provide a new material and method for making black printer separation images.

A still further object is to provide a new, simple and reproducible process for color-and-tone-correction of separation films.

Other objects of our invention are to provide a new process of correcting for the unwanted absorptions of printing inks; to provide a new process of color correction without color development or dye images; to provide a new process of color correction which is controlled by chemical means and wherein neither registration nor reregistration of a mask with the original or with a separation film is necessary to provide a method of color masking which eliminates the appearance of moir patterns in color-corrected prints.

These and other objects of our invention are achieved by making our color-and-tone-corrected separation image-producing film and using it to prepare the corrected separation image of a multicolor original image for making printing plates to print the color inks needed to reproduce the multicolor original image. In its simplest form our unitary color-and-tone-correcting separation image-producing film comprises:

(1) A transparent support having coated thereon (2) A first light-sensitive layer that is a color-and-tonecorrecting silver separation image-forming layer containing a hydrophilic colloid silver halide emulsion layer that is capable of recording a light image of at least one primary color and (3) A removable superposed second light-sensitive layer containing a hydrophilic colloid silver halide emulsion that is capable of recording a light image of at least one primary color that is different from that recorded by the said first layer.

The removable second light-sensitive layer is advantageously separated from the first light-sensitive layer by a separate stripping layer to facilitate easy removal of the said removable layer. Antihalation and light filtering layers are advantageously used in our elements. Where a light-absorbing filter is needed between the first and second light-sensitive layers, the appropriate light filtering dye(s) is added to the separate stripping layer, advantageously.

The first and second light-sensitive layers of our ele ments are spectrally sensitized according to the separation negative to be produced and the correction desired. The first light-sensitive layer is sensitized to light having the complimentary color to the color of the ink that will be printed by the printing plate that will be made from the separation negative film. In addition, the first light-sensitive layer may also be sensitive to another part of the spectrum provided that the second light-sensitive layer is sensitive to light from still another part of the spectrum. The second light-sensitive layer is usually sensitized to light that is complimentary in color to the color of the ink having the unwanted absorption that is to be corrected for in the separation negative. If the sensitivity of the second light-sensitive layer overlaps the sensitivity of the first-light-sensitive layer, light in a portion or all of the overlapping part of the spectrum is advantageously filtered by an appropriately colored filter either integral to or external to the element in the path of the exposing light.

For example, a cyan ink printing plate that is corrected for unwanted red absorption of the magenta ink (printed by the magenta ink printing plate) is advantageously made from one of our tone-and-color-correcting separation negative elements that has a red-, or a red-and-bluesensitive first light-sensitive layer and a green-, or a greenand-blue-sensitive second light-sensitive layer. A blue-light absorbing filter is advantageously used to prevent blue light from recording on the light-sensitive layers.

A yellow ink printing plate that is corrected for unwanted blue absorption by the magenta ink or unwanted blue absorption by the magenta and cyan inks is advantageously made from one of our tone-and-color-correcting separation elements that has a blueor a blue-and-redsensitive first light-sensitive layer separated from a greenand-blue-sensitive second light-sensitive layer by a bluelight-absorbing filter layer. A magenta ink printing plate that is corrected for unwanted green absorption by the cyan ink is advantageously made from one of our toneand-color-correcting separation elements that has a greenand-blue-sensitive (i.e., orthochromatically sensitized) first light-sensitive layer and a red and green and blue (i.e., panchromatically sensitized) second light-sensitive layer in this element. A blue-light-filtering layer is used advantageously to prevent blue light from being recorded on either layer and a green-light-absorbing filter is advantageously placed between the first and second lightsensitive layers Our novel film is advantageously exposed through its support to a light image from a multicolor original. The image-exposed film is then developed in a black-andwhite developer solution to silver images in both lightsensitive layers. Then the film is washed, fixed, washed and dried. An acid stop bath is advantageously used be tween the development step and fixing step. The removable second light-sensitive layer is advantageously removed from the film during this process after the development step and prior to drying. The layer with the unitary color-and-tone-corrected silver separation image remaining on the film support after removal of the removable layer (and completion of the process) is ready for making the appropriate printing plate.

The removal of the top emulsion layer may be effected by various means well known in the art. If a separate stripping layer is used, the entire top emulsion layer may be stripped from the underlying layer for removal according to well known procedures. Such stripping layers may be of polyvinyl alcohol, cellulose ether phthalate, unhardened gelatin, etc. as described, for example, in U.S. Pats. 2,725,293 and 3,148,063. The use of a low jelly strength gelatin as a vehicle for the top emulsion results in a coating which can be washed away with warm water eliminating the need for a separate stripping layer.

Alternately water soluble polymers such as polyvinyl alcohol, as described in U.S. Pat. 2,725,296, cellulose ether phthalate, etc., may be used as the vehicle for the top emulsion. The salt effect in the developer prevents dissolution of such layers during processing. Washing in warm water effects the complete removal of the layer.

The tone-and-color-correct image-forming elements of our invention advantageously contain any of the hydrophilic colloid-silver halide emulsions, preferably emulsions which contain silver bromoiodide dispersed in one or a mixture of hydrophilic colloids useful in photographic emulsions. These colloids include such naturally occurring materials as gelatin, albumin, agar-agar, gum arabic, alginic acid and such synthetic hydrophilic resins as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose ether, partially hydrolyzed cellulose acetate, etc. In some of our elements it is advantageous to use in the second light-sensitive (upper) emulsion layer a silver bromoiodide emulsion whose grains contain from about 1 to about 20 mole percent silver iodide and at least about 1 mole percent more iodide than the silver halide grains in the first light-sensitive (lower) emulsion layer.

Any of the well-known optical sensitizing dyes, including the cyanine and merocyanine dyes, such as those described in U.S. Pats. 1,846,301; 1,846,302; 1,942,854; 2,112,140; 2,15,338; 2,493,747; 2,739,964; 2, 493,743; 2,503,776; 2,519,001; 2,666,761; 2,734,900; 2,739,149; British patent 450,958, etc. are used to advantage to optically sensitize our silver halide emulsions.

The emulsions used are advantageously chemically sensitized by well-known procedures. The emulsions can be digested with naturally active gelatin, or sulfur compounds can be added as described in U.S. Pats. 1,574,944; 1,623,499; and 2,410,689. The emulsions can be treated with salts of noble metals as described in U.S. Pats. 2,448,060; 2,399,083; 2,597,856; 2,597,915; etc. The emulsions can contain sensitizing amounts of reducing agents, such as, stannous salts (U.S. Pat. 2,487,850), polyamines, such as are described in U.S. Pats. 2,518,698; 2,521,925; etc., and speed increasing compounds, such as, those described by U.S. Pats. 2,271,623; 2,288,226; 2,334,864; 2,866,437; etc.

Any of the well-known transparent support materials used in photographic elements are used to advantage in our elements, including glass, cellulose acetate, cellulose nitrate, other synthetic film forming resins, e.g., the polyesters, the polyamides, polystyrenes, etc.

Any of the well-known light-filtering dyes are used to advantage in the light-filtering and antihalation layers of our elements, including cyanine, merocyanine, styryl, cinnamylidene, oxanol dyes, etc. such as those described in U.S. Pats. 2,298,733; 2,537,472; 2,622,082; 2,691,579; 2,843,486; 2,856,404; 3,247,127, etc. Any of the wellknown ultraviolet absorbing materials are used to advantage in our elements including the compounds described by U.S. Pats. 2,685,512; 2,719,086; 2,719,162; 2,739,888; 2,739,971; etc. These dyes and/or ultraviolet absorbing compounds are advantageously dispersed in any of the hydrophilic colloids used in photographic layers including those mentioned previously. Any of the wellknown mordants are used to advantage to hold the filter dye in its layer. Particularly efficacious are combinations of acid substituted filter dyes with basic mordants including the mordants of Minsk U.S. 2,882,156.

According to one embodiment of our invention, toneand color-corrected separation films are prepared in the following manner.

The color original to be reproduced is photographed through appropriate filters onto the separation film material of our invention to separately prepare a red-filter separation, a green-filter separation, a blue-filter separation and a black-printer separation negative. The filter 1ayer(s) and/or specific spectral sensitivities of the individual emulsions govern the exposure and spectral response of each of the two superimposed sensitive layers. The exposed elements are then developed in a conventional black-and-white developing solution whereby a silver image that is a color-and-tone-corrected primary-color separation negative image is produced in the first lightsensitive layer and a silver image is produced in the removable second light-sensitive emulson layer.

The development of the image in the lower emulsion layer (i.e., first light-sensitive layer) is selectively inhibited by, for example, by-products of the development of the image in the upper emulsion layer (i.e., removable second light-sensitive layer). After development, the upper emulsion layer is removed by stripping or dissolving, etc. The lower layer contains, after subsequent fixing, washing and drying, the chemically tone-and-color-corrected image.

The mechanism whereby the development of the record in the first light-sensitive layer is depressed by the development of the record in the superposed second lightsensitive layer is not entirely understood. It is assumed that several of the factors which in the photographic art are believed to be the cause for the so-called interimage effects contribute to the inhibition of the image formation in the first light-sensitive layer of our invention. Thus development oxidation products: liberated halide ions such as bromide or iodide; developer exhaustion; and/ or other factors influencing development may be the basis for the desired inter-layer development effects according to our invention. One means of providing the desired masking effect is also obtained by the use of inhibitor-releasing couplers such as those described in U.S. patent 3,148,062, issued Sept. 8, 1964. The desired development inhibition efiects is also obtained by the use of inhibitor-releasing developers such as those disclosed in the Belgian Pats. 645,713 and 645,794. Furthermore, the development depression afforded by the non-metallic development byproducts according to U.S. Pat. 2,712,995, issued July 12, 1955, is also relied upon to selectively modify the development of the image recorded in the color-and-tonecorrecting silver separation image-forming layer of our material. Alternatively, in the case where each of the two emulsion layers contains incorporated developing agents, the relative amounts or kinds of incorporated developing agent in the upper and the lower layers is advantageously adjusted to control the degree of development in the bottom layer as a function of the depletion of the developing agent in the top layer. For, in this manner, unused developing agent in the top layer becomes available by diffusion for development in the lower layer inversely proportional to the extent of development in the top layer.

The separation irnageforming silver halide emulsion layer of our film is optionally either a medium-contrast emulsion adapted to record continuous tones, or a highcontrast lithographic emulsion designed to record halftone and/or fineline images. When the separation imageforming layer is of medium contrast, continuoustone separations are made followed by an exposure there through and through a halftone screen onto the printing plate material or onto other negatively or positively working materials for further image control which is desired for certain applications. When the separation layer is of high contrast, corrected direct halftone separations are made using a crossline or a contact screen during the photographing of the original image onto the separation films. The following two techniques can advantageously be used for making such a direct halftone separation:

(1) Each of the two emulsion layers is exposed through a separate filter. The color-correcting layer is exposed without using a screen and the separation layer exposure is made with a screen.

(2) Both emulsion layers are exposed simultaneously through the base of the film with the screen in place. A filter interlayer between the two emulsions is made to scatter the light reaching the color-correcting layer so as to destroy the halftone image pattern in this layer. Alternatively, the desired color correcting elfect is obtained with a halftone record in both of the emulsion layers.

The invention, its objects, advantages, and the principles involved will be more clearly understood from the following illustrations when read in connection with the foregoing disclosures.

FIG. 1 shows the arrangement of layers in a red-filtercolor-correcting separation film (the cyan printer) according to one embodiment of our invention.

Removable second light-sensitive hydrophilic colloid silver halide emulsion layer 11 having high green sensitivity is carried on a clear interlayer 12 which is superposed on the first light-sensitive hydrophilic colloid silver halide emulsion layer 13 having low green and high red sensitivity. A clear support 14 carries an antihalation layer 15 beneath a minus-blue broad filter layer 16.

The masking film of FIG. 1 is exposed to a color original with white light through the support whereby a green record is formed in the top layer which is later removed and discarded, and a red record in the bottom layer which becomes the tone-and-color-corrected separation. The processing effects associated with the developing of the green record in the top layer corrects the silver image in the bottom layer for the unwanted red absorption of the magenta printing ink.

FIG. 2 shows the arrangement of layers in a greenfilter tone-and-color-correcting separation film (magenta printer).

Removable second light-sensitive hydrophilic colloid silver halide emulsion layer 21 having panchromatic sensitivity is carried on a red-dyed interlayer 22 which is adjacent to an orthochrornatically sensitized hydrophilic colloid silver halide emulsion layer 23. A clear support 24 carries an antihalation layer 25 beneath a minus-blue broad filter layer 26.

A White light exposure through the support produces a red record in the top layer which is later removed and discarded, and a green record in the permanent bottom layer which becomes the separation negative. The processing effects associated with the development of the red record corrects the silver image in the bottom layer for the unwanted green absorption of the cyan ink.

FIG. 3 shows the arrangement of layers in a blue-filter color-correcting separation film (yellow printer). Removable hydrophilic colloid silver halide emulsion layer 31 having orthochromatic sensitivity is carried on a yellow dyed interlayer 32 on top of a blue-sensitive hydrophilic colloid silver halide emulsion layer 33. A transparent film support 34 carries an antihalation layer 35 beneath an ultraviolet absorbing layer 36.

A white light exposure through the support produces a green record in the top layer which is later removed, and a blue record in the second light-sensitive layer which becomes the tone-and-color-corrected separation negative image. The processing effects associated with the development of the top green record corrects the silver image in the bottom layer for the unwanted blue absorptions of the magenta and cyan inks.

In another embodiment of our invention adapted to provide for correction of more than a single primary color, the sensitivity of the emulsion layer and filter layers are made accordingly. For example, a single film might serve as both a red-filter and blue-filter automatic correcting separation material. Such a film shown in FIG. 4 contains a blue-green-sensitive second light-sensitive hydrophilic colloid silver halide emulsion layer 41 over a yellow filter layer 42 on top of a first light-sensitive hydrophilic colloid silver halide emulsion layer 43 sensitive to blue and red only. The antihalation layer 45 is on the opposite side of clear support 44; the filtering action is provided by external filters at the time of exposure. In order to obtain a color-corrected blue-separation film, such an element is exposed to the original through the support by using a cyan filter.

The processing effects associated with the development of the green record in the removable upper emulsion layer correct for the unwanted blue absorption of the magenta and cyan inks used to print the blue color. In order to obtain a color-corrected red-separation film, the above element is exposed to the original through the support by using a yellow filter. The processing effects associated with the development of the green record in the removable upper emulsion corrects the silver images developed in the bottom layer for the unwanted red absorption of the magenta ink.

A correcting black printer advantageously has the structure shown in FIG. 5. The top layer 51 comprises a panchromatically sensitized hydrophilic colloid silver halide emulsion which is sharp cutting at about 600 m and is coated on a red filter interlayer 52 having a sharp cut-oif at about 560 mu, e.g., a Kodak Wratten filter No. 23A. Panchromatically sensitized hydrophilic colloid silver halide emulsion layer 53 is next to the transparent support 54 which contains on the opposite side an antihalation layer 55.

A White light exposure through the support produces a record in the top layer with wavelengths between 560 and 600 m Processing eifects resulting from development of the top layer correct the record in the bottom layer so that after processing including the removal of the removable layer, use of the corrected image in the separation material to print a black ink printing plate will result in a black printer that will not print black ink in areas of the print that should have saturated colors.

interlayer development effects can be exaggerated by various means. Thus limited agitation; emulsion layers of limited permeability; emulsion binders or layers of limited buffering or accepting capacity for bromide, iodide or hydrogen ions; developer solutions low in hydrogen, bromide or iodide ion buffering capacity; developing agents like chlorohydroquinone with a high coefiicient of dilution, like hydroquinone and p-phenylenediamine types which are easily repressed in their developing action by bromide or iodide ions, like pyrogallol and hydroquinone which are easily repressed in their developing action by addition of acid, like monomethyl p-aminophenol whose oxidized form inhibits further development; and low concentration of developing agent, alone or in combination, contribute to exaggerated interlayer development effects.

For a preferred embodiment of our invention, the chemical masking effect is obtained by providing an upper silver halide emulsion layer which contains a higher mole percent of silver iodide than the lower emulsion layer. Accordingly, the upper emulsion layer preferably contains (a) silver bromoiodide grains whose iodide content constitutes from about 1 to about 20 mole percent of the silver halide, and (b) at least about 1 mole percent more iodide than the silver halide grains in the lower emulsion layer.

The following specific examples will serve to illustrate this embodiment of the invention. In all cases, the hardened gelatin layers contained mucochloric acid as the hardener. All coverages are expressed in mg./ft.

COATING NO. 2.BLUE SEPARATION NEGATIVE MASK FILM WITH WASH-OFF EMULSION Gelatin Silver Top coat. Unhardened gelatin 82 Blue-green Unhardened gelatin-silver brornoio- 750 450 sensitive. dide emulsion 6 mole percent iodide. Filter layer Unlliardened gelatin yellow colloidal 6 s1 ver. Interlayen... Unhardened gelatin Blue sensi- Hardened gelatiirsilver bromoiodide 580 480 tive. emulsion, 2 mole percent iodide. Support Cellulose acetate Antihalation. Gelatin layer having a 0.2 neutral 440 density.

COATING NO. 3.-BLUE SEPARATION NEGATIVE MASK FILM CONTAINING A STRIPPING LAYER Gelatin Silver Top coat. Hardened gelatin 82 Blue-green. Hardened gelatin-silver bromoiodide 750 450 emulsion. 6 mole percent iodide. Stripping 31 mg. of cellulose ether phthalate 14 6 layer. Blue sensi- Hardened gelatin-silver bromolodide 580 480 tive. emulsion, 2 mole percent iodide. Support Cellulose acetate Antihalatiom- Gelatin layer having a 0.2 neutral 440 density.

COATING NO. 4.GREEN SEPARATION NEGATIVE MASK FILM CONTAINING A SIRIPIING LAYER Gelatin Silver Top c0at Hardened gelatin 82 Blue-red Hardened gelatin-silver bromoiodide 720 450 sensitive. emulsion, 6 mole percent; iodide. Filter laycr Hardened, mordanted, and magenta- 240 dyed gelatin layer. stlripping 31 mg. of cellulose ether phthalate 14 ayer. Blue-green Hardened gelatin-silver bromoiodide 580 480 sensitive. emulsion, 2 mole percent iodide. Support Cellulose acetate Antihalation- Gelatin layer having a 0.2 neutral 440 density.

COATING NO. 5.RED SEPARATION NEGATIVE MASK FILM WITH A WASH-OFF EMULSION COATING NO. 6.BLACK PRINTER SEPARATION NEGA- TIVE MASK FILM CONTAINING A STRIPPING LAYER Sharp cutting at 560 m Stripping 31 mg. of cellulose ether phthalate per 14 ayer. square foot. Panchro- Hardened gelatin-silver bromoiodide 578 290 matie. emulsion, 2 mole percent iodide. Support Cellulose acetate Antihalatiom- Gelatin layer having a 0.2 neutral 440 density.

Appropriate filters are used to control the desired exposures in each light-sensitive layer. The following description illustrates the masking obtained, as an example, by the use of color separation negatives of the structure shown as coating No. 1.

Two separate exposures were made through the support side of the film. The first exposure through an intensity scale test object (step tablet) in one orientation, the second exposure through the same test object in another orientation obtained by rotating the test object through an angle of 90. The first exposure was made through a Kodak Wratten filter No. 29 (red) for 15 seconds using an exposure of about four foot-candles at the film plane. The second exposure was made through a Kodak Wratten filter No. 61 (green) for 15 seconds using the same exposure as above. The film was developed in Developer A, below, for 3 minutes at a temperature of 68 F., fixed, washed, removable layers removed and the corrected green separation dried. The equivalent percent masking was 41 at a density of 1.0.

The equivalent percent masking:

A effective speed change A log E mask X10070 with the A effective speed change being measured at a specific density (1.0 in this example).

10 Coatings Nos. 2 to 6 were appropriately exposed, processed, and evaluated in a similar manner by the use of filters and development conditions as indicated below.

Kodak Wratten filter Equivalent for exposure of- Developers percent Coating and time of masking No. Upper layer Lower layer development (density=l.0)

3-.. d do A-3 minutes 22 5... golggrrlalemyfl. #29(red) d0 47 15 ye ow e .do do 46 It will be seen that one of the advantages of our chemical method of color correction is the differential degree of correction in highlight, intermediate and shadow areas. The degree of development depression is greatest in those areas wherein the unwanted absorption is greatest. The correction increases with increasing density. The percent of masking is higher at higher densities. This is in marked contradistinction to simple photographic masking where all areas are nonselectively masked to the same extent. For specific purposes of toneand/or color-correction, the photographic elements of our invention can be constructed and processed such that both light-sensitive emulsion layers yield a positive image or that one of the layers yields a positive and the other of the layers a negative image.

When high-contrast lith type emulsions are used in our element, these are advantageously exposed to crossline, contact screen or random dot screen either during manufacture in a pro-screening operation or during the photographic exposure process.

The drawing and examples of our elements have the antihalation layers placed on the support side away from the light-sensitive layers, however, it is to be understood that the antihalation layer can also be placed between the support and the first light-sensitive layer. Also, when our elements require an antihalation layer as well as a light filter such as a blue-light-absorpting filter as in FIG. 2, or an ultraviolet-absorpting layer as in FIG. 3, the antihalation layer and light-absorpting layer obviously can be combined into a single layer.

The invention has been described in detail with particular reference to preferred embodiment thereof, but it will be understood that variations and modifications can be affected within the scope and spirit of the invention as described hereinbefore and as defined in the appended claims.

We claim:

1. A light-sensitive black-and-white photographic separation-negative film for making a unitary color-and-tone correcting-separation-negative image of a multicolor original, said film comprising:

(1) a transparent support having coated thereon,

(2) a first light-sensitive layer that is a color-and-tone correcting-silver-separation-negative image forming layer containing a hydrophilic colloid silver halide emulsion that is sensitive to and capable of recording a light image of at least one primary color, and

(3) a removable superposed silver-image-forming layer that is sensitive to and capable of recording a light image of at least one primary color that is different from that recorded by said first layer, said removable layer containing silver brornoiodide with at least one mole percent more iodide than the silver halide in said first layer;

said separation-negative film being capable, upon exposure to said multicolor original, of forming upon development a unitary color-and-tone-correcting-silver-separationnegative image in said first layer and a silver negative image in said removable layer which is adapted for easy removal following development, leaving the said unitary color-and-tone-correcting silver-separation-negative image as the sole image on the processed film.

2. A light-sensitive black-and-white photographic separation-negative film comprising:

(1) a transparent support having coated thereon,

(2) an antihalation layer,

(3) a first light-sensitive layer that is a color-and-tonecorrecting silver-separation-negative-image forming layer containing a hydrophilic colloid-silver bromoiodide emulsion that is sensitive to and capable of recording a light image of at least one primary color,

(4) a removable hydrophilic colloid interlayer, and

(5) a removable superposed second light-sensitive hydrophilic colloid-silver bromoiodide emulsion layer that is sensitive to and capable of recording a negative image of a light image of at least one primary color that is different from that recorded by said first layer, said removable layer containing silver halide with at least one mole percent more iodide than the silver bromoiodide emulsion in said first light-sensitive layer, said removable hydrophilic colloid interlayer being located between said first light-sensitive layer and said second light-sensitive layer.

3. A photographic separation-negative film of claim 2 in which the said transparent support has coated in succession on one side, the said antihalation layer and an ultraviolet-absorbing layer and in which are coated in succession on the other side of said support, the said first light-sensitive layer, the said removable interlayer and the said second light-sensitive layer, and in which the first light-sensitive layer is a blue-sensitive gelatino silver bromoiodide emulsion, the said removable interlayer contains a blue light-absorbing dye, and the said second light-sensitive layer is an orthochromatically sensitized gelatino silver bromoiodide emulsion layer.

4. A photographic separation-negative film of claim 2 in which the said antihalation layer is coated on one side of said support and in which the said support has coated in succession on the other side a first light-sensitive layer, a removable interlayer and a second light-sensitive layer and in which the said first light-sensitive layer is a blueand-red-sensitive gelatino silver bromoiodide emulsion layer, the said interlayer contains a blue light-absorbing dye and the said second light-sensitive layer is a blue-andgreen sensitive gelatino silver bromoiodide emulsion layer.

5. A photographic separation-negative film of claim 2 in which the said antihalation layer is coated on one side of said support, and in which the said support has coated in succession on the other side, the first light-sensitive layer, the said removable interlayer, and the said second light-sensitive layer, and in which the said first light-sensitive layer is a panchromatically sensitized gelatino silver bromoiodide emulsion, the said removable interlayer contains a dye having a sharp absorption cut-off at about 560 Il'l/L and in which the said second light-sensitive layer has a panchromatically sensitized silver bromoiodide emulsion having a sharp sensitization cut-oft at about 600 m 6. A photographic separation-negative film of claim 2 that has an ultraviolet-absorbing layer coated over said antihalation layer, and said removable interlayer between the firstand second-sensitive layers contains a dye that absorbs light to which said first light-sensitive layer is sensitive and transmits light to which said second lightsensitive layer is sensitive.

7. The light-sensitive black-and-white photographic separation-negative film of claim 2 in which the silver bromoiodide in said second light-sensitive layer has six mole percent iodide and the silver bromoiodide in said first light-sensitive layer has two mole percent iodide.

8. A photographic separation-negative film of claim 2 in which the said transparent support has coated in succession on one side, the said intihalation layer and a blue light-absorbing filter layer and in which the said first lightsensitive layer, said removable interlayer and said removable second light-sensitive layers are coated in succession on the opposite side of said support.

9. A photographic separation-negative film of claim 8 in which the said first light-sensitive layer is red sensitized and the said second light-sensitive layer is green sensitized.

10. A photographic separation-negative film of claim 8 in which the said first light-sensitive layer is orthochromatically sensitized, the removable interlayer contains a green light-absorbing dye and the said second light-sensitive layer is panchromatically sensitized.

11. A process for preparing a unitary colorand tonecorrected separation image from a multicolor original, said separation image being useful for the preparation of a color printing plate to print one subtractive color ink, which separation image is corrected so that a color printing plate made from it compensates for the unwanted absorption of at least one of the remaining subtractive color printing inks, said process comprising the steps of:

(1) producing in a multilayer film, a latent separation image in a first silver halide emulsion layer primarily sensitive to at least one color region corresponding to the said separation, and a latent image in a second silver halide emulsion layer primarily sensitive to at least one color region different from the first said layer, the said first silver halide emulsion layer being coated on a clear support and the said second silver halide emulsion layer being adapted for easy removal and being superposed on the said first silver halide emulsion layer on the same side of said support, said film containing light-filtering means for confining the exposure of at least one of said silver halide emulsion layers to particular regions of the spectrum, the combination of light-filtering means with the said second silver halide emulsion layer restricting the exposure therein to at least one of the primary color regions corresponding to said subtractive colored printing ink having unwanted absorption in the color region corresponding to the primary sensitivity of the said first silver halide emulsion layer, the said latent images being made by exposing said multilayer film to light from said multicolor original through the said support,

(2) producing a unitary color-and-tone-corrected silver separation image in the said first silver halide emulsion layer and a silver image in the said second lightsensitive layer by contacting the said second silver halide emulsion layer with an aqueous alkaline developer solution so that by-products of development of the silver image in the said second silver halide emulsion layer inhibits development of the latent image to a silver image in the said first silver halide emulsion layer sufliciently to correct the separation image for the said unwanted light-absorption,

(3) removing the said second silver halide emulsion layer leaving the color-and-tone-corrected separation image as the sole silver image in the processed film.

12. The process of claim 11 for preparing a silver separation image that is tone-and-color-corrected for unwanted red absorption of magenta printing ink, said separation image being made for preparing the cyan ink printing plate, said process using a multilayer film in which the first silver halide emulsion layer is red-sensitive, the second silver halide emulsion layer is green-sensitive and separated from the said first layer by a clear removable hydrophilic colloid interlayer, and the light-filtering means comprises a blue absorbing filter and a superposed antihalation layer on the side of the support opposite to the silver halide emulsion layers.

13. The process of claim 11 for preparing a silver separation image that is tone-and-color-corrected for unwanted green absorption of the cyan printing ink, said separation image being made for preparing the magenta ink printing plate, said process using a multilayer film in which the first silver halide emulsion layer is orthochromatically sensitized and the second silver halide emulsion layer is panchromatically sensitized, and the light filtering means comprises a green absorbing removable filter interlayer between the said first and second emulsion layers, and a blue-light absorbing filter.

14. The process of claim 11 for preparing a silver separation image that is tone-and-color-corrected for unwanted blue absorption of magenta and cyan printing inks, said separation image being made for preparing the yellow ink printing plate, said process using a multilayer film in which the first silver halide emulsion layer is bluesensitive and the second silver halide emulsion layer is orthochromatically sensitized and the light filtering means comprises a blue-light absorbing removable filter interlayer between the said first and second emulsion layers, and an ultraviolet-absorbing filter.

15. The process of claim 11 for preparing from a multicolor original a silver separation image that is tone-andcolor-corrected for unwanted blue absorption of magenta and cyan printing inks, said separation image being made for preparing the yellow ink printing plate, said process using a multilayer film in which the first silver halide emulsion layer is blueand red-sensitive and the second silver halide emulsion layer is blueand green-sensitive, and the light filtering means comprising a blue absorbing removable filter interlayer between the said first and second emulsion layers, exposure of said multilayer film to light from said multicolor original being made through a redlight-absorbing filter.

16. The process of claim 11 for preparing from a multicolor original a silver separation image that is tone-andcolor-corrected for the unwanted red absorption of ma genta printing ink, said separation image being made for preparing the cyan ink printing plate, said process using a multilayer film in which the first silver halide emulsion layer is blueand red-sensitive, and the second silver ha lide emulsion layer is blueand green-sensitive, and the light filtering means comprising a blue absorbing removable filter interlayer between said first and second emulsion layer, exposure of said multilayer film to light from said multicolor original being made through a blue-lightabsorbing filter.

References Cited UNITED STATES PATENTS 2,367,665 1/1945 Capstaff et al. 96-71 2,492,954- 1/1950 Ball et al. 9671 2,611,696 9/1952 Keyes et al 96-69 2,725,296 11/1955 Kendall 96-69 NORMAN G. TORCHIN, Primary Examiner A. T. SURO PICO, Assistant Examiner US. Cl. X.R.. 96-71, 84, 

